package code3;


import java.util.ArrayList;

/**
 * @author noob
 * @version 1.0
 * @date 2021/3/18 12:53
 */
public class AVLTree<K extends Comparable<K>,V>  {

    private class Node{
        public K key;
        public V value;
        public Node left, right;
        public int height;

        public Node(K key, V value){
            this.key = key;
            this.value = value;
            left = null;
            right = null;
            this.height = 1;
        }
    }

    private Node root;
    private int size;

    public AVLTree(){
        root = null;
        size = 0;
    }

    //获得节点的高度
    private int getHeight(Node node){
        if(node == null){
            return 0;
        }
        return  node.height;
    }

    //判断二叉树是否是一颗二分搜索树
    public boolean isBST(){
        //中序遍历--有序就满足
        ArrayList<K> keys = new ArrayList<>();
        inOrder(root,keys);

        //判断数组是不是升序的
        for (int i = 1; i < keys.size(); i++) {
            if(keys.get(i-1).compareTo(keys.get(i))>0){
                return false;
            }
        }
        return true;
    }

    private void inOrder(Node node, ArrayList<K> keys) {
        if(node == null){
            return;
        }
        inOrder(node.left,keys);
        keys.add(node.key);
        inOrder(node.right,keys);

    }

    //判断一颗树是不是平衡二叉树
    public boolean isBalanced(){
        return isBalanced(root);
    }

    private boolean isBalanced(Node node) {
        if(node==null){
            return  true;
        }
        int balanceFactor = getBalanceFactor(node);
//        System.out.println("xxxx:"+balanceFactor);
        if(Math.abs(balanceFactor) > 1){
            return false;
        }

        return isBalanced(node.left) && isBalanced(node.right);

    }


    //计算平衡因子的方法
    private int getBalanceFactor(Node node){
        if(node == null){
            return 0;
        }
        return getHeight(node.left) - getHeight(node.right);
    }





    // 向二分搜索树中添加新的元素(key, value)
    public void add(K key, V value){
        root = add(root, key, value);
    }

    // 向以node为根的二分搜索树中插入元素(key, value)，递归算法
    // 返回插入新节点后二分搜索树的根
    private Node add(Node node, K key, V value){

        if(node == null){
            size ++;
            return new Node(key, value);
        }

        if(key.compareTo(node.key) < 0) {
            node.left = add(node.left, key, value);
        } else if(key.compareTo(node.key) > 0) {
            node.right = add(node.right, key, value);
        } else { // key.compareTo(node.key) == 0  需要覆盖旧值
            node.value = value;
        }
        //以当前node的节点添加一个节点之后，需要更新height
        node.height = 1 + Math.max(getHeight(node.left),getHeight(node.right));

        //计算平衡因子
        int balanceFactor = getBalanceFactor(node);
//        if( Math.abs(balanceFactor) > 1) {
//            System.out.println("unbalanced:" + balanceFactor);
//        }
            //不平衡--需要旋转
            //LL
            if(balanceFactor > 1 && getBalanceFactor(node.left) >= 0){
                //左侧的左右增加了一个结点
                return rightRotate(node);
            }
            //RR
            if(balanceFactor < -1 && getBalanceFactor(node.right) <= 0){
                return  leftRotate(node);
            }
            //LR
            if(balanceFactor > 1 && getBalanceFactor(node.left) < 0){
                node.left= leftRotate(node.left); //先换位LL
                return rightRotate(node);
            }
            //RL
            if(balanceFactor < -1 && getBalanceFactor(node.right) >0){ //左子树比右子树高
                node.right = rightRotate(node.right);
                return leftRotate(node);
            }


        return node;
    }

    //右旋转操作
    // 对节点y进行向右旋转操作，返回旋转后新的根节点x
    //        y                              x
    //       / \                           /   \
    //      x   T4     向右旋转 (y)        z     y
    //     / \       - - - - - - - ->    / \   / \
    //    z   T3                       T1  T2 T3 T4
    //   / \
    // T1   T2
    private Node rightRotate(Node y){
        Node x = y.left;
        Node T3 = x.right;
        //向右旋转
        x.right = y;
        y.left=T3;
        //更新结点的高度
        y.height= Math.max(getHeight(y.left),getHeight(y.right))+1;
        x.height= Math.max(getHeight(x.left),getHeight(x.right))+1;

//        System.out.println("xxx"+getBalanceFactor(x));
        return  x;
    }



    // 对节点y进行向左旋转操作，返回旋转后新的根节点x
    //    y                             x
    //  /  \                          /   \
    // T1   x      向左旋转 (y)       y     z
    //     / \   - - - - - - - ->   / \   / \
    //   T2  z                     T1 T2 T3 T4
    //      / \
    //     T3 T4
    private Node leftRotate(Node y) {
        Node x = y.right;
        Node T2 = x.left;

        // 向左旋转过程
        x.left = y;
        y.right = T2;

        // 更新height
        y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;
        x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;
        return x;
    }



    public V remove(K key) {
        Node node = getNode(root, key);
        if(node != null){
            root = remove(root, key);
            return node.value;
        }
        return null;
    }


    private Node remove(Node node, K key){

        if( node == null ) {
            return null;
        }

        Node retNode;
        if( key.compareTo(node.key) < 0 ){
            node.left = remove(node.left , key);
            retNode = node;

        }
        else if(key.compareTo(node.key) > 0 ){
            node.right = remove(node.right, key);
            retNode = node;

        }
        else{   // key.compareTo(node.key) == 0

            // 待删除节点左子树为空的情况
            if(node.left == null){
                Node rightNode = node.right;
                node.right = null;
                size --;
                retNode= rightNode;
            }else

            // 待删除节点右子树为空的情况
            if(node.right == null){
                Node leftNode = node.left;
                node.left = null;
                size --;
                retNode= leftNode;
            }else{
                // 待删除节点左右子树均不为空的情况

                // 找到比待删除节点大的最小节点, 即待删除节点右子树的最小节点
                // 用这个节点顶替待删除节点的位置

                Node successor = minNode(node.right);
//            successor.right = removeMin(node.right);
                successor.right = remove(node.right,successor.key);
                successor.left = node.left;

                node.left = node.right = null;

                retNode= successor;
            }

        }
        //根据retNode来维护平衡
        if(retNode == null){
            return  null;
        }

        //以当前node的节点添加一个节点之后，需要更新height
        retNode.height = 1 + Math.max(getHeight(retNode.left),getHeight(retNode.right));

        //计算平衡因子
        int balanceFactor = getBalanceFactor(retNode);
//        if( Math.abs(balanceFactor) > 1) {
//            System.out.println("unbalanced:" + balanceFactor);
//        }
        //不平衡--需要旋转
        //LL
        if(balanceFactor > 1 && getBalanceFactor(retNode.left) >= 0){
            //左侧的左右增加了一个结点
            return rightRotate(retNode);
        }
        //RR
        if(balanceFactor < -1 && getBalanceFactor(retNode.right) <= 0){
            return  leftRotate(retNode);
        }
        //LR
        if(balanceFactor > 1 && getBalanceFactor(retNode.left) < 0){
            retNode.left= leftRotate(retNode.left); //先换位LL
            return rightRotate(retNode);
        }
        //RL
        if(balanceFactor < -1 && getBalanceFactor(retNode.right) >0){ //左子树比右子树高
            retNode.right = rightRotate(retNode.right);
            return leftRotate(retNode);
        }


        return  retNode;

    }


    // 返回以node为根的二分搜索树的最小值所在的节点
    private Node minNode(Node node){
        if(node.left == null) {
            return node;
        }
        return minNode(node.left);
    }

    // 删除掉以node为根的二分搜索树中的最小节点
    // 返回删除节点后新的二分搜索树的根
    private Node removeMin(Node node){

        if(node.left == null){
            Node rightNode = node.right;
            node.right = null;
            size --;
            return rightNode;
        }

        node.left = removeMin(node.left);
        return node;
    }





    public boolean contains(K key) {
        return getNode(root, key) != null;
    }


    public V get(K key) {
        Node node = getNode(root, key);
        return node == null ? null : node.value;
    }

    //辅助函数--- 返回以node为根节点的二分搜索树中，key所在的节点
    private Node getNode(Node node, K key){

        if(node == null) {
            return null;
        }

        if(key.equals(node.key)) {
            return node;
        } else if(key.compareTo(node.key) < 0) {
            return getNode(node.left, key);
        } else { // if(key.compareTo(node.key) > 0)
            return getNode(node.right, key);
        }
    }


    public void set(K key, V newValue) {
        Node node = getNode(root, key);
        if(node == null) {
            throw new IllegalArgumentException(key + " doesn't exist!");
        }

        node.value = newValue;
    }


    public int getSize() {
        return size;
    }


    public boolean isEmpty() {
        return size==0;
    }





    public static void main(String[] args){

        System.out.println("Pride and Prejudice");

        ArrayList<String> words = new ArrayList<>();
        if(FileOperation.readFile("pride-and-prejudice.txt", words)) {
            System.out.println("Total words: " + words.size());

            AVLTree<String, Integer> map = new AVLTree<>();
            for (String word : words) {
                if (map.contains(word)) {
                    map.set(word, map.get(word) + 1);
                } else {
                    map.add(word, 1);
                }
            }

            System.out.println("Total different words: " + map.getSize());
            System.out.println("Frequency of PRIDE: " + map.get("pride"));
            System.out.println("Frequency of PREJUDICE: " + map.get("prejudice"));
            System.out.println("is BST? "+ map.isBST());
            System.out.println("is Balanced? "+ map.isBalanced());
            for (String word:words){
                map.remove(word);
//                if(map.isBST() || map.isBalanced()){
//                    throw  new IllegalArgumentException("ERROR");
//                }
            }
        }

        System.out.println();


    }


}
